Tuesday 10 January 2012

A Blog Summary

I'm afraid that my time blogging on the anthropogenic disturbance of the global nitrogen cycle is drawing to a close..... In order to make the most of the information posted, and for me to have a personal refresher on a few things that I may have forgotten, I thought that I would try and produce a short summary of the key messages from the blog.

To start with, I'm conscious that I have not yet explained my blog title, I chose the 'Destroying life support' bit because that it exactly what the nitrogen cycle is - life support.  Without the creation and transportation of reactive nitrogen in various forms, the earth could not support the levels of primary production that currently occur on the planet. The unfortunate situation is that through the advancement of the technologies (most notably the Haber-Bosch process and fossil fuel use in energy and transport) that have allowed the Earth to support so many additional lives, we are adding to the cycle in a way that is very damaging environmentally.

The anthropogenic disturbance on the global nitrogen cycle is a dramatic one. The cycle is changing faster than any other, due to a level of man-made influence which far outstrips our impact on the carbon cycle  (Nr creation has increased by 120% since 1970 (Galloway et al., 2008). The environmental problems caused by this have been discussed and shown in several posts e.g. nitrogen's dark side, the nitrogen cascade and posts on eutrophication, acidification, diversity loss and impacts on the atmosphere and ocean.

Just as important, and more interesting to me personally, were the interactions between various different environmental processes arising from the disturbance of the N cycle.  This was discussed early on in the post on Gruber and Galloway's earth-system approach and continued as a theme throughout in posts describing the impact of acidification on the ocean nitrogen cycle and the impact of oceanic nitrogen pollution on the atmosphere.

There was also some research thrown up which I found particularly unusual or surprising.  For example, the work of Pregitzer et al. in Michigan where they found that inputs of Nr in forests increased the carbon sequestration of not only the plants, but also soils due to alteration of the forest microbial community.  An excellent insight into past anthropogenic influence on Nr was described in the post on Holtgrieve et al. (2011), whose work analysing lake sediment records showed that anthropogenic disturbance has been happening since the late 19th century, a time earlier than thought previously.  I feel that this was the most significant paper to be published during my time writing the blog.

Finally, I think possibly the most important topic for future management of the N cycle was the discussion of the nitrogen footprint calculator devised by Leach et al. in to bring the problem to the public's attention and emphasise the role that individual choices can play.  Whilst writing the blog it quickly became apparent that the issues of excess Nr were appearing fairly frequently in scientific literature, but it was a challenge to find anything at all in the general media or even something as simple as a youtube video that might engage a wider audience.  Things became easier as I found my way around the subject, but it appears that this issue is largely hidden from view.  I believe this has a massive impact on the potential for managing the Nr problem, as public awareness is essential, particularly when our lifestyles and consumer choices (e.g. cutting back on overconsumption of meat and dairy) could do so much towards solving this major environmental problem.

I hope that the blog has given an informative and accessible insight into the disturbance of the global nitrogen cycle and has perhaps encouraged some people to consider the impact that their daily activities can have.

Thanks for reading!

Ed 

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